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Author
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Topic: Leaving the lunar module ascent stage in orbit
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ASCAN1984
Member Posts: 1049
From: County Down, Nothern Ireland
Registered: Feb 2002
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posted 03-09-2010 03:45 PM
   
I was just thinking the other night about after the ascent stage of each lunar module being allowed to crash into the moon a few days after the crew left lunar orbit. This is a shame if you consider the historic significance. How possible would it have been to leave the lunar module in lunar orbit until today? |
SpaceAholic
Member Posts: 4494
From: Sierra Vista, Arizona
Registered: Nov 1999
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posted 03-09-2010 04:09 PM
Not all; Snoopy (Apollo 10) remains in heliocentric orbit. |
ilbasso
Member Posts: 1522
From: Greensboro, NC USA
Registered: Feb 2006
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posted 03-09-2010 04:21 PM
The lunar mascons (mass concentrations) were not well understood in Apollo days. They had only been discovered a few years previously during the Lunar Orbiter missions. Because the mascons result in variability of lunar gravity as you fly over the surface, and with solar wind pressure, it is very difficult to leave an unpowered spacecraft in lunar orbit for a prolonged period. Put it in too low an orbit, and it crashes before long; put it higher up, and you might lose it to the chaotic effects of Earth, moon and sun's gravity. They would have needed to carry a lot of extra fuel for the RCS thrusters to keep an ascent stage in low orbit, and they didn't have the luxury of being able to carry any extra weight that was not needed for landing and for ascent/rendezvous. |
SpaceAholic
Member Posts: 4494
From: Sierra Vista, Arizona
Registered: Nov 1999
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posted 03-09-2010 06:53 PM
Better possibility would have been parking in either the Earth/Moon L4 or L5 position. |
ilbasso
Member Posts: 1522
From: Greensboro, NC USA
Registered: Feb 2006
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posted 03-10-2010 02:09 PM
quote:
Originally posted by SpaceAholic:
Snoopy (Apollo 10) remains in heliocentric orbit.
Snoopy's orbit is chaotic, though. It is gravitationally perturbed by close approaches to the moon and Earth, so that its precise (or even approximate) location is not known and is not predictable. |
NASAROB
Member Posts: 38
From: Astoria NY
Registered: Feb 2009
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posted 03-11-2010 08:58 AM
Wasn't the purpose of crashing the ascent stage to use ALSEP to measure it and help learn about the lunar interior? |
music_space
Member Posts: 1179
From: Canada
Registered: Jul 2001
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posted 03-11-2010 04:05 PM
Has recent robotic lunar imagery shown us ascent stage crash sites? |
Max Q
Member Posts: 399
From: Whyalla South Australia
Registered: Mar 2007
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posted 03-11-2010 06:21 PM
Unless I remember incorrectly Snoopy's assent stage engine was remotely fired to to get an idea on the amount of fuel remaining in the tanks. |
Fra Mauro
Member Posts: 1624
From: Bethpage, N.Y.
Registered: Jul 2002
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posted 03-11-2010 11:50 PM
Snoopy was also fired out of lunar orbit to make absolutely sure it wouldn't be a hazard for Apollo 11. |
Lou Chinal
Member Posts: 1332
From: Staten Island, NY
Registered: Jun 2007
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posted 03-15-2010 05:38 PM
How long could an object stay at a Lagrangian Point in space? The James Webb Telescope will be launched on a five year mission to L2. Will the mscons/solar wind effect be that great? What about a passing comet?Is L2 more stable then L4 or L5? I assume it's longer than five years, but is it 50 years or more like 500? |
ilbasso
Member Posts: 1522
From: Greensboro, NC USA
Registered: Feb 2006
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posted 03-15-2010 06:00 PM
Even the Lagrange points are not entirely gravitationally stable. The distance between the moon, Earth and sun are constantly changing. Any object orbiting about a Lagrange point will still need to expend propellant to stay in place. |
SpaceAholic
Member Posts: 4494
From: Sierra Vista, Arizona
Registered: Nov 1999
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posted 03-15-2010 09:48 PM
Not true for the Earth Moon L4/L5. Coriolis results in a stable, self-correcting orbit around those two positions. |
ilbasso
Member Posts: 1522
From: Greensboro, NC USA
Registered: Feb 2006
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posted 03-19-2010 02:03 PM
Impact site of the Apollo 14 LM (Antares) ascent stage has been found. See here. |
LM-12
Member Posts: 3324
From: Ontario, Canada
Registered: Oct 2010
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posted 09-11-2016 03:07 PM
The Apollo 9 lunar module ascent stage remained in Earth orbit for over 12 years before it re-entered in October 1981. |
One Big Monkey
Member Posts: 171
From: West Yorkshire, UK
Registered: Jul 2012
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posted 09-15-2016 01:09 PM
There is another aspect to this, in that if it is in an unstable or unpredictable lunar orbit it is in the way for future missions. If it is deliberately crashed it isn't a hazard any more! |
Wehaveliftoff
Member Posts: 2343
From:
Registered: Aug 2001
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posted 09-22-2016 02:35 PM
quote:
Originally posted by LM-12:
The Apollo 9 lunar module ascent stage remained in Earth orbit for over 12 years before it re-entered in October 1981.
If it was headed from a SE to N/NE direction as it reentered earth's atmosphere, I witnessed its reentry Oct 23, 1981. |
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